A seal damaged or missing piston alone can not be held responsible for the creeping stem of the cylinder, the seal gland end of the rod must also be damaged and leakage at the same time.

If the seal gland is damaged, then steals the stem downward by gravity and a heavy load, can make up fluid to start the vacuum that rod out of the cylinder, and moves in the free atmosphere. The presence of this liquid makeup can explore. Without it, the solution would be to create a team of space they would keep in place.

In this case, the makeup air is. The air is indeed a very useful liquid (no liquid) for use in bottles, especially if you do not mind vague, non-positive movement, and you do not operate at high pressures.

If the pole is pointing up or down, we learned that the lack of piston seal will not let blocked on a single rod cylinder with cylinder fluid drive or ports when the seal gland is rampant compromised.

If you know that your bottle is, in fact, if the ports seem to slip around the directional valve, and yet the end of the rod gland seal leakage is not allowed, where are the real cause?

The check valve of the management itself is often the cause. It can not be closed, the “A” and “B” cylinder ports operate completely. The valve may be worn or it is not because of his return to the position half-closed. The cause of valve problems will be covered in future newsletters.

The last time we looked at single rod cylinders, which are pointed with their stems extending towards the sky.

We found that the directional valve closed two ports of the cylinder is the only way to push the cylinder down to allow the loss of fluid outside of the bottle. We have found that can not fall down the rod and the piston, otherwise a solid cylinder of liquid no additional space for the volume of steel that has the trunk.

Lets end this week with a look at the bottles that are attached to the head. The stem of the cylinder extends downward.

Again, this is a fairly common misconception that a worn piston seal to move fluid to the piston rod side of the cylinder side, crawl so in line.

We will start with the directional control valve is closed (we ball valves at each cylinder port in the vicinity has just made clear) and the stem is fully retracted. Suppose that the cylinder is filled with hydraulic fluid.

If the piston seal is absent, and we have to crawl a load on the cylinder rod?

When the bottle full of steel (piston and rod was) and liquid () largely non-compressible fluid, what would happen if the parent does not give creep into the expansion?

If the rod goes well, the cylinder open and closed, the amount of volume occupancy lose accordingly. What fills the gap which is generated inside the cylinder?

A large force (heavy) pulling on the end of the stalk may cause some expansion, but the whole movement would be very low. Since the blank would be very long in a tiny fraction of an inch.

And a heavy burden lifted, the forces of labor, the cylinder down. But if ports are closed by valves, which blocked the flow path?

 It popular is that the piston seal is broken inside the cylinder and the movement of drift occurs because the fluid by gravity under pressure is forced by the piston. But is this possible?

Can a single rod cylinders really behave in this manner when the piston seal fails?

To answer these questions we need to consider some basic principles of volume.

Imagine a six-foot, 6 “diameter pipe closed at one end and sitting on a surface. Imagine that the hose is already filled with liquid. Then you come to drop with a length of 2 inch diameter rod in solid steel pipe open end at the top.
What happened? Liquid overflows and spills, because the pipe was already full. He was put in place over the line for the volume of steel in him and you because of the displaced liquid was left.
cylindermyth6

Now consider a vertical cylinder with the tip of the stem upward. Rod End gland and seal are in good shape.

Let’s start with the stem fully extended, and suppose that there is no air in the fluid under the piston. The cylinder is lifting a heavy load. Both the ground (barrel end) and above (rod end) will be closed ports ball valves.

If we now remove the piston seal, so there is a noticeable gap between the piston and cylinder wall, what will happen?
If the piston and rod assembly, or it will drift down in his seat?

Activity: Study and learning with simulate picture thus as below ,Understand Label prefill and decompression components. Complete sequencing of press controls .
The hydraulic press depends crucially Pascal pressure in a closed system is constant. At one end of the system, a piston is driven by a small cross-section of a lever to increase strength. Small-diameter pipe leads to the other end of the system. See the simulate picture thus as below .

Pascal’s Law: The pressure in a confined liquid is transmitted intact and acts with equal force on equal areas and 90 degrees to the vessel wall.

A liquid, as oil is displaced when the piston is pushed inward. The small piston for a given distance of movement, moves a smaller scale than the large piston, which is the ratio of the area of the piston head proportionately. Therefore, the small piston must be moved to move a large distance to the piston big to escape. The distance between the piston moves at great distance the piston moves, divided by the ratio of surface, the piston head. Thus energy is conserved in the form of work in this case and the law of conservation of energy is satisfied. Work is force multiplied by distance, and it increases with the force exerted on the piston greater the distance the force must be reduced excessively.

Here are some examples:

* Bale dryerPulp mill or plate for journalists
* Plywood Press
* Feed compactor

Picture1. Clamping Function

* Filter-press residue
Press * Aluminum extrusion profile
* Press Box
* Trash compactor

Decompression

At the end of the cycle the press ram material pressed, the fluid in the RAM is still under pressure. Properly control the speed of decompression than pull the ram is a serious problem that is common to most hydraulic presses. If you’ve ever heard, and believed that the hydraulic oil is not compressible, you must open your mind to some new learning. It is true that the hydraulic oil is not very compressible in comparison with gas such as air (used in plant air compressors), but this is not the end of history.

Picture2. controlling the rate of decompression

Without compression, so the available 400 Volume girl is filled with 400 gallons of hydraulic fluid.

Most heating oil hydraulic compression of about half of one percent per 1000 PSI hydraulic pressure. This means that at 1000 PSI, you can customize 502.5 gallons to 500 gallons ram. 5000 PSI, you can customize 512.5 gallons to 500 gallons of the same ram.
prefill3

The pressure, 512.5 gal were crammed into an area of 500 gal.

Typical work as an industrial printing press extruding aluminum and packaging pulp has a very large cylinder (or RAM) can have several gallons (10 liters) or more of the liquid completely compressed to the maximum pressure when fully deployed. This is a huge amount of potential energy.

Trap and pressure (5000 psi) The volume of 512.5 gallons of liquid in the RAM 500 gallons will print very quickly when the valve port opens to expose liquid to atmospheric pressure.

Under compression have been crammed into the 500 gal space.

Compress hydraulic fluids have been carried out gradually and controlled as the ram was moved against the load (feature extraction). The output of this compressed fluid must be carefully controlled. Decompression is usually treated by opening the valve a very small hole. Once atmospheric pressure has fallen to a level, the valve is opened for the cycle to withdraw quickly and efficiently.
prefill4

Decompression is begun with the opening doll relief, which allows controlled release of hydraulic fluid booster.

If the fluid is released at a pace not controlled as it is through the large port valve, which was immediately transferred to the highest position, the liquid moves at very high speeds. This outburst of energy cons wall tubes, which are essentially sub-during this period may cause pressure buildup in May of the same fracture line. Hose back in May diametrically boule sudden decompression of ram, and thus may contract length and separate installation or detachment of the wall surrounding the tank online.
hosedamage

Small diameter of the cylinder press, as used in trash compactors, food May appears decompression control. Those bottles with smaller volumes and lower pressures may be only a small amount of compressed fluid in the end of the race. Hydraulic components generally inexpensive to include only bang-bang style directional valve that releases fluid from the totally blind end port at the end of the cylinder stroke. The effects of uncontrolled decompression, it is still often heard and felt the shock wave is amplified by a metal cover the whole machine. Even these low volume shocks can have a devastating effect over time.

In the next issue of newsletter to learn, we will examine some specific decompression valve to control the vertical and horizontal presses.

Activity: Check and verify to Interpret catalogue data and operational specifications.

The debate over the control of hydraulic servo-valve was interesting. But the whole debate revolves around the ability to digital control of analog servo valve control. There are other considerations in the application of hydraulic servo valves for industrial applications.

Both the hydraulic cylinders and hydraulic servo-driven actuators have limited benefits of oil in compression (in the fall of oil). For cylinders the length of the race determines the oil trapped under the compression will be, and this determines the resonance will be hydraulically. A figure of merit than the resonance of not less than 200 rad / sec for a stable servant.

Hydraulic resonance = square root (2B ^ Dm 2/Jt Ve)
where B = compressibility = lb / in ^ 2
Dm = Motor displacement = ^ 3/rad
Jt = total inertia of the motor = lb-in-sec ^ 2
Ve = volume of oil under compression in ^ 3 =

To rotary actuators in which the valve of the servo is directly connected to the engine through a manifold, can hold around 60 Hz or more without a load on the engine. Most of the hydraulic servo can not bear any lateral load on the bearings in the end, the motor shaft. Therefore, a coupling device such as a Thomas joints needed to deviation from the crankshaft to minimize the load shaft. These links are much larger inertia inertia of the crankshaft. This requirement reflects the load inertia of the machine is connected to the engine also reduces the hydraulic resonance. The result of this tax, yet reduces the bandwidth of servo-hydraulic machine industry for about 15 to 20 Hz

In general, if a servo-drive is a requirement which he was very torquey power is not enough torque, the hydraulic servo-course. The unity of the criteria for sizing hydraulic servos found resonance hydraulic high enough. The servo-valve is a 2-stage device. The output stage is the placement of the coil of the motor. The input stage is one of a range torque electric motor and a very high impedance which must be accompanied in the servo valve controller. The servo valve amplifier can be designed in house if you know what you do or suppliers capable of this amp

Activity: For your work ,you should be make the valve disassembly, inspection, test and reassembly.

Cartridge Valves is the interior of a control valve are off the shelf components with a standard, so that they are easy to fill a block owned by the valve. They are available in different configurations, on / off, proportional, pressure relief valves, etc. Life in general in a valve block and are electrically controlled to provide logic and automated functions.
Could you see simulate thus as below.

Objective: Present and Demonstrate appropriate skills regarding effective system operations with animation for hydraulic system fundamental.

Activity: To understand for design and motion control solution exercises.

Thus as below is master regenerative circuits diagram and pressure control system.

Objective: Fundamental and Explain proportional valve principles and make basic adjustments

Activity: User learning and understanding in valve disassembly, inspection and reassembly

Picture below show process of valve.

Brittle Magnetic Leads
Problem statement :
    The continued use of the magnetic coil over a period of time is a fragile cable insulation. This creates the possibility of isolation and / or broken wire can cause a short circuit in the magnet coil
Cause of the error are:
                         1. The drivers are generated by the coil affects the heart. This situation is exacerbated by high ambient temperatures.
2. Hydraulic fluid type can be eaten or isolation.
3. Coolant can be used by the machine to destroy the insulation.

Magnets fireproof exposed to liquids:
Problem statement :
    The exposure of magnetic coils fire resistant fluids such as phosphate esters will lead shorts between windings of the coil. These liquids also dissolve the varnish on the coil and magnet-black color. The liquid on the insulation of the wires go, so it has become too vague and leave eventually. This condition can be avoided through the purchase of magnetic coils or rolls that are compatible with corrosive liquids.

Cause of failure:

1. Chemical reaction with the magnet.
Solenoid failure – burns continuous output current coil of nylon boot cast causes of failure:
1. Mechanical stop
2. Line voltage low
3. Overtemperature
4. Acceleration cycle.
5. Excessive or high-voltage line.

Solenoid failure – shorted:
Problem statement :
1. Refrigerants containing metal shavings
2. Voltage transients
3. Fire resistant fluids

Solenoid failure – Mechanical destruction
Problem statement :
1. Surge
2. Cycle on Rates
3. Zealous mechanic.

Solenoid shorted:
Problem statement :
A magnet for use in or near water coolant are saturated with fine particles of metal susceptible to short-circuit between coil cable links
Cause of the error are:
1. Soaking the cooling coil.